Flash Communication: Ti-Catalyzed “Interrupted” Cascading Hydroamination of 1,6- and 1,7-En-ynes

Abstract

Herein, we report a new hydroaminative cyclization for 1,6- and 1,7-en-ynes using a simple Ti imido precatalyst, [py2TiCl2(NPh)]2. The well-known Ti imido + alkyne [2 + 2] azatitanacyclobutadiene cycloadduct intermediate can be further intercepted via insertion by tethered alkenes, followed by protonolysis of the resultant metallacycle to yield α-carbocyclic imine products through cascading C–N and C–C bond formation.